Production of cellulosic materials with oxidizing power



United States Patent Ofiice 330,273 Patented Jan. 24, 1967 3,300,273 PRODUCTION OF CELLULOSIC MATERIALS WITH OXIDIZING POWER Russell M. H. Kullman, Metairie, and Robert M. Reinhardt and John G. Frick, In, New Orleans, La., assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed June 24, 1963, Ser. No. 290,263 8 Claims. (Cl. 8-116.3)

A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all the purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to the treatment of cellulosic materials. The object of this invention is to prepare cellulosic materials such as fabric, yarn, rope, linters, or batting that have oxidizing power and that contain positive chlorine, but do not suffer autodegradation in storage or use.

It is known that the treatment of cellulosic textiles, to which an amide-formaldehyde condensate has been applied, with inorganic hypochlorites results in the formation of chloramides on the textiles. The retained chlorine in this form is positive chlorine, and has oxidizing power. Cellulosic textiles containing this chlorine, however, lose strength on storage, particularly at elevated temperatures. The strength loss is due to the formation of acids from the retained chlorine. For this reason, the retention of positive chlorine is generally considered disadvantageous, and rarely is use made of the oxidizing power of the textile with retained chlorine.

The object of this invention can be attained by chemically modifying the cellulosic textile or other material so that it contains chemically bound phosphonic acid groups. The textile is then treated with an amide-formaldehyde condensate and the bound phosphonic acid groups are converted to the salt form with alkali-metal cations before treatment with sodium hypochlorite solution. After treatment with hypochlorite the textile retains oxidizing chlorine, and is less susceptible to strength loss on standing or use, even at elevated temperatures.

Chemical modification of the cellulosic material for the purpose of this invention can be accomplished by etherification of a portion of the cellulosic hydroxyl groups with a group containing a phosphonic acid substituent. An example of this is the etherifieation of cellulose with chloromethylphosphonic acid to form a partially phosphonomethylated cellulose as described by Hobart et al. in Textile Research Journal, volume 29, number 11, pages 884-889, November 1959. For this invention, modifications giving from about 0.03 to about 0.1 phosphonomethyl group for each anhydroglucose unit of the cellulose are suitable.

The amide-formaldehyde condensates useful in this invention are those that are commonly used in finishing cellulosic textiles for special properties, such as wrinkle resistance, and that are not specifically designed to avoid chlorine retention. Typical examples are N-methylol carboxylic amides, dimethylolurea, and methylol ureas of lower substitution. These may be applied to the modified cellulosic materials in the same manner as they are applied to unmodified cellulosic textiles. Such an application typically consists of the treatment of the cellulosic material with an aqueous solution of the amide-formaldehyde condensate followed by drying and heat treatment. The acidic catalysts used in the treatment of unmodified cellulosic textiles, however, can be omitted in many cases with the modified cellulosic materials containing phosphonic acid groups.

An application to give from about 0.1 to about 3.0% nitrogen content on the modified cellulose is satisfactory for the purpose of this invention.

Conversion of the phosphonic acid groups to the salt form after treatment with the amide-formaldehyde condensate is accomplished by washing the treated materials with solutions made mildly alkaline by the addition of alkali metal bases, such as sodium hydroxide, sodium carbonate, potassium carbonate, or mixtures of these. A wash at pH 8 to pH 11 is suitable for this purpose. Introduction of positive chlorine is accomplished most economically by treatment with aqueous solutions of alkali metal hypochlorites, such as the sodium hypochlorite commonly used for bleaching textiles. It may be accomplished, however, by the use of organic hypochlorites or chloramines. In most cases conversion of the phosphonic acid groups to the salt, and introduction of positive chlorine can be accomplished in a single step.

The reduced tendency to lose strength in the chlorinecontaining cellulosic textiles of this invention is apparently due to the protective action of the alkali metal salt against the acids formed by the chlorine. The fact that such salt is chemically a part of the cellulose and not merely deposited on or within it, therefore, is advantageous. The textile so modified can be retreated after the chlorine originally introduced is reduced by use or by prolonged storage without loss of the protective agent by leaching in the retreatment.

The products of this invention are useful for the oxidation of materials in solution whereby the residue of reduced oxidizing agent, in the form of a textile product or loose insoluble material can be readily removed to minimize contamination of the solution. They are also useful for making protective clothing whereby a wearer can be protected from injurious materials that can be rendered innocuous by oxidation.

The following examples illustrate the invention in further detail.

Example 1 Cotton print cloth was phosphonomethylated by the process described by Hobart et al., op. cit., to a D.S. of 0.04 (an average of 0.04 phosphonomethyl group for each anhydroglucose unit of the cellulose).

This fabric was treated with urea-formaldehyde precondensate which had been prepared 'by the reaction of 0.235 mole of formaldehyde with 0.133 mole of urea at pH 8 for 16 hours. The phosphonomethylated cotton was padded to about wet pickup with a solution containing 7.5% of the urea-formaldehyde precondensate and 0.32% zinc nitrate catalyst, mounted on pin frames, dried for seven minutes at 60 C., cured for three minutes at 160 C., afterwashed with an alkaline solution of a nonionic detergent, and tumble dried. Nitrogen content of the washed fabric was 1.82%; breaking strength (by test method D3 9-59 of the American Society for Testing Materials) in the warp direction for 30.6 lbs.

A portion of the vphosphonomethylated fabric treated with urea-formaldehyde was chlorinated with a solution of sodium hypochlorite containing 0.25% available chlorine at a pH of 9.5, thoroughly rinsed, and air dried. Analysis of the fabric by titration of the iodine released from acidified potassium iodide solution showed that it contained 0.49% available chlorine, and had an oxidizing capacity of meq./kg. of sample. The fabric had a breaking strength of 29.4 lbs. after chlorination and scorching by Tentative Test Method 92-1958T of the American Association of Textile Chemists and Colorists. The chlorinated fabric, therefore, retained 96% of its original strength after the standard scorch test for damage caused by retained chlorine.

Example 2 A sample of unmodified cotton print cloth was treated with urea-formaldehyde precondensate as in Example 1. The fabric contained 1.71% nitrogen, and had a breaking strength of 24.1 lbs. When chlorinated as in Example 1, the fabric contained 0.35% available chlorine but retained only 38% of its original strength after the standard scorch test for damage caused by retained chlorine.

Example 3 A sample of the phosphonomethylated cotton as described in Example 1 was treated with a 7.5% solution of a urea-formaldehyde precondensate containing no catalyst. Preparation and application of the precondensate were performed as described in Example 1. The fabric contained 2.01% nitrogen, and had a breaking strength of 37.6 lbs. When chlorinated as described in Example 1, the fabric contained 0.54% available chlorine but retained 89% of its original strength after the standard scorch test for damage caused by retained chlorine.

We claim:

1. A process for preparing a chemically modified cellulosic textile that exhibits oxidizing power and resists autodegradation comprising:

(a) phosphonomethylating the cellulosic textile to etherify the cellulose hydroxyl groups to a degree of substitution of about from 0.03 to 0.1 phosphonomethyl group per anhydroglucose unit of the cellulose;

(b) resin-treating the resulting phosphonomethylated cellulosic textile with an amide-formaldehyde condensate which retains chlorine when treated with a chlorinating agent, by impregnating the phosphonomethylated cellulosic textile with an aqueous solution containing a sufficient quantity of the amideformaldehyde condensate to give a 0.1% to 3.0% nitrogen content on the phosphonomethylated cellulosic textile, followed by heating the impregnated cellulosic textile to dry and cure it;

(c) converting the phosphonic acid radicals of the phosphonomethyl groups of the resin-treated, phosphonomethylated cellulosic textile to the alkali metal salt form by washing the textile with an alkaline solution containing an alkali metal base; and

(d) treating the resulting cellulosic textile with a chlorinating agent selected from the group consisting of an alkali metal hypochlorite, an organic hypochlorite, and a c-hloramine which introduces positive chlorine into the amide-formaldehyde condensate.

2. The process of claim 1 wherein the amide-formaldehyde condensate is a urea-formaldehyde condensate.

3. The process of claim 1 wherein the resin-treating of the phosphonomethylated cellulosic textile is carried out in the presence of an acidic catalyst.

4. The process of claim 1 wherein the chlorinating agent is an alkali metal hy-pochlorite.

5. A process for preparing a chemically modified cellulosic textile that exhibits oxidizing power and resists autodegradation comprising:

(a) phosphonomethylating the cellulosic textile to etherify the cellulose hydroxyl groups to a degree of substitution of about from 0.03 to 0.1 phosphonomethyl group per anhydroglucose unit of the cellulose;

(b) resin-treating the resulting phosphonomethylated cellulosic textile by impregnating it with an aqueous solution containing a quantity of an amide-formaldehyde condensate, which retains chlorine when treated with a chlorinating agent, sufiicient to give a 0.1% to 3.0% nitrogen content in the phosphonomethylated cellulosic textile, followed by heating the impregnated cellulosic textile to dry and cure it; and

(c) treating the resin-treated, phosphonomethylated cellulosic textile with an alkaline solution containing an alkali metal hypochlorite which thereby converts the phosphonic acid radicals of the phosphonomethyl groups of the resin-treated, phosphonomethylated cellulosic textile to the alkali metal salt form and introduces positive chlorine into the amideformaldehyde condensate.

6. The process of claim 5 wherein the amide-formaldehyde condensate is a urea-formaldehyde condensate.

7. The process of claim 5 wherein the resin-treating of the phosphonomethylated cellulosic textile is carried out in the presence of an acidic catalyst.

8. The process of claim 5 wherein the alkali metal hypochlorite is sodium hypochlorite.

References Cited by the Examiner UNITED STATES PATENTS 2,584,114 2/1952 Daul et al. l17l39.4 2,824,779 2/1958 Reeves et a1. 8129 X 3,041,199 6/1962 Miller et al.

OTHER REFERENCES Frick et al., Textile Research Journal, April 1957, pages 294299.

Reid et al., Textile Industries, November 1958, pages 2-10.

Reinhardt et al., Textile Research Journal, October 1959, pages 802810.

Hobart et al., American Dyestulf Reporter, Feb. 6, 1961, pages 30-34.

NORMAN G. TORCHIN, Primary Examiner. H. WOLMAN, Assistant Examiner. 

1. A PROCESS FOR PREPARING A CHEMICALLY MODIFIED CELLULOSIC TEXTILE THAT EXHIBITS OXIDIZING POWER AND RESISTS AUTODEGRADATION COMPRISING: (A) PHOSPHONOMETHYLATING THE CELLULOSIC TEXTILE TO ETHERIFY THE CELLULOSE HYDROXYL GROUPS TO A DEGREE OF SUBSTITUTION OF ABOUT FROM 0.03 TO 0.1 PHOSPHONOMETHYL GROUP PER ANHYDROGLUCOSE UNIT OF THE CELLULOSE; (B) RESIN-TREATING THE RESULTING PHOSPHONOMETHYLATED CELLULOSIC TEXTILE WITH AN AMIDE-FORMALDEHYDE CONDENSATE WHICH RETAINS CHLORINE WHEN TREATED WITH A CHLORINATING AGENT, BY IMPREGNATING THE PHOSPHONOMETHYLATED CELLULOSIC TEXTILE WITH AN AQUEOUS SOLUTION CONTAINING A SUFFICIENT QUANTITY OF THE AMIDEFORMALDEHYDE CONDENSATE TO GIVE A 0.1% TO 3.0% NITROGEN CONTENT ON THE PHOSPHONOMETHYLATD CELLULOSIC TEXTILE, FOLLOWED BY HEATING THE IMPREGNATED CELLULOSIC TEXTILE TO DRY AND CURE IT; (C) CONVERTING THE PHOSPHONIC ACID RADICALS OF THE PHOSPHONOMETHYL GROUPS OF THE RESIN-TREATED, PHOSPHONOMETHYLATED CELLULOSIC TEXTILE TO THE ALKALI METAL SALT FORM BY WASHING THE TEXTILE WITH AN ALKALINE SOLUTION CONTAINING AN ALKALI METAL BASE; AND (D) TREATING THE RESULTING CELLULOSIC TEXTILE WITH A CHLORINATING AGENT SELECTED FROM THE GROUP CONSISTING OF AN ALKAI METAL HYPOCHLORITE, AN ORGANIC HYPOCHLORITE, AND A CHLORAMINE WHICH INTRODUCES POSITIVE CHLORINE INTO THE AMIDE-FORMALDEHYE CONDENSATE.
 5. A PROCESS FOR PREPARING A CHEMICALLY MODIFIED CELLULOSIC TEXTILE THAT EXHIBITS OXIDIZING POWER AND RESISTS AUTODEGRADATION COMPRISING: (A) PHOSPHONOMETHYLATING THE CELLULOSIC TEXTILE TO ETHERIFY THE CELLULOSE HYDROXYL GROUPS TO A DEGREE OF SUBSTITUTION OF ABOUT FROM 0.03 TO 0.1 PHOSPHONOMETHYL GROUP PER ANHYDROGLUCOSE UNIT OF THE CELLULOSE; (B) RESIN-TREATING THE RESULTING PHOSPHONOMETHYLATED CELLULOSIC TEXTILE BY IMPREGNATING IT WITH AN AQUEOUS SOLUTION CONTAINING A QUANTITY OF AN AMIDE-FORMALDEHYDE CONDENSATE, WHICH RETAINS CHLORINE WHEN TREATED WITH A CHLORINATING AGENT, SUFFICIENT TO GIVE A 0.1% TO 3.0% NITROGEN CONTENT IN THE PHOSPHONOMETHYLATED CELLULOSIC TEXTILE, FOLLOWED BY HEATING THE IMPREGNATED CELLULOSIC TEXTILE TO DRY AND CURE IT; AND (C) TREATING THE RESIN-TREATED, PHOSPHONOMETHYLATED CELLULOSIC TEXTILE WITH AN ALKALINE SOLUTION CONTAINING AN ALKALI METAL HYPOCHLORITE WHICH THEREBY CONVERTS THE PHOSPHONIC ACID RADICALS OF THE PHOSPHONOMETHYL GROUPS OF THE RESIN-TREATED, PHOSPHONOMETHYLATED CELLULOSIC TEXTILE TO THE ALKALI METAL SALT FORM AND INTRODUCES POSITIVE CHLORINE INTO THE AMIDEFORMALDEHYDE CONDENSATE. 